JPS60187236A - Rotor field winding for electric machine - Google Patents

Abstract

PURPOSE:To prevent copper from being abraded between thin layers, by connecting the layers of rotor field windings at a set interval. CONSTITUTION:Winding insulators 43 are provided between winding layers. The insulators 43 are provided with slots according to similar slots for copper conductors 42, so that cooling fluid passages 46 may be formed. Thin layers connected in parallel are brazed at an interval in the longish direction of slots. The layers can be brazed easily because of partial work, and the built-in property of windings is not spoiled. Copper grains are prevented from being generated from the relative motion of the thin layers to copper, by the brazing for controlling the relative motion. Thus, a grounding accident or layer short-circuit accident can be avoided.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a cylindrical directly cooled rotor field winding in a turbine generator or the like, and particularly to the relative relationship between the field windings that occurs during operation of these devices. The present invention relates to a field winding suitable for preventing wear of the field winding due to movement.

[Background of the invention]

Large-scale generators require extensive cooling, so the stator is constantly cooled using water or other fluids, and the rotor is generally cooled using hydrogen gas. It is trace. Here, a typical structure of a rotor of a turbine generator will be explained. As shown in FIG. 1, the rotor has a cylindrical rotor core, and the rotor field winding 3 is housed in longitudinal slots provided along the outer periphery of the rotor core. The field winding consists of a conductor that is placed at the bottom within a pair of slots closest to the pole faces and then passed through the next winding until it reaches a position near the top of the slot. The layers are helically stacked into a pair of slots. The stacked windings are shown in FIG. A similar winding is then continued in each pair of rotor slots, and such windings are repeated for the desired number of slot pairs. Similarly, current flow through these windings follows the conductive paths described above. Since the conductors are typically flat conductor bars of copper, an insulating layer is placed between adjacent copper layers in the slots to keep the rotor pole windings wound in series. has been done. Regarding cooling, in order to cool the conductor in the slot, holes are provided in the conductor rod along its longitudinal direction in accordance with the cooling method, and the holes provided in each conductor rod are adjacent to each other. The holes in the conductor rods are aligned to form suitable cooling passages. For cooling the area outside the slots of the rotor winding, copper conductor rods are connected in parallel to the rotor field winding, and each conductor rod is provided with grooves, and the grooves of the conductor rods are aligned with each other to form cooling passages. is formed.

The conductor rods of these windings are connected in parallel by brazing at a portion of the winding corner outside each slot.

There is no need to insert insulating material between the conductor rods connected in parallel in this way. However, it has recently been noted that when the windings are so constructed, copper wear problems can occur. That is, copper particles accumulate due to mechanical wear between these parallel connected copper layers. For clarity, the term "layer" as used in this specification refers to the series connected pole winding sections. Also, the term ``lamina'' shall refer to adjacent parallel-connected conductive winding sections. A layer is therefore composed of one or more lamellae. It is these thin layers that can contain passageways.

While the generator is operating normally at relatively high speeds, no significant movement appears between adjacent thin nodes.

The reason for this is thought to be that a large centrifugal force is generated to hold the rotor's conductor rods in almost the same position.

However, in some cases, this generator does not generate 4 forces and the speed of the rotor is maintained by moving the machine (by means of a turning device) in such a way as to prevent deflection or deformation of the rotor body. be.

It is believed that this low speed operation causes relative movement between adjacent laminae connected in parallel. Since no electrically insulating material is inserted between these laminas, the laminas are in mechanical contact along the longitudinal direction of the rotor slot, and therefore due to the relative movement between the laminas, the steel Wear of the material may occur. This wear can cause copper particles to accumulate, resulting in ground fault problems in the rotor winding circuit.

Regarding this wear of copper between thin layers, published patent No. 57-7
5543r Electrical Machine Rotor with Mechanical Separator'' has been proposed, which provides between the thin layers an anti-wear material consisting of a polyester material reinforced with glass fibers.

However, in this case, the winding height in the slot depth direction becomes high, so it is necessary to increase the slot depth. This results in hindering miniaturization of the generator.

In addition, Fig. 3 shows the slot end winding structure when the anti-wear material 22 is provided. A compressive force due to this centrifugal force is concentrated on the anti-wear material. Therefore, the surface pressure that the anti-wear material receives is approximately 1.5 of the surface pressure that the interlayer insulation material receives.
Since the amount is more than twice as high, there is concern that the anti-wear material may be damaged.

[Purpose of the invention]

It is an object of the present invention to provide a novel rotor field winding which prevents copper wear between adjacent parallel connected laminae of the rotor winding and improves life span.

[Summary of the invention]

During operation, copper powder accumulates due to mechanical wear between the thin layers in the rotor pole line straight section of the turbine-generated Tlj rock, resulting in a ground fault or an interlayer short circuit. In order to prevent these drawbacks, the present invention prevents mechanical wear by joining the thin layers of the rotor field winding at certain intervals, thereby eliminating the generation of copper particles and preventing ground faults or glabella shorts. This is to prevent

[Embodiments of the invention]

FIG. 4 illustrates a rotor of a turbine generator. The present invention can be applied to such a direct cooling machine. The rotor l has a substantially cylindrical iron core 30. iron core 30
A slot 31 extends in the longitudinal direction on the outer periphery. Magnetic pole 350 windings are slotted a and a', b and b', C and C'
, d and d'. The windings of the opposite pole are arranged symmetrically in the same way in the other slots. The layers of windings are arranged in slots a and a', b and b', C and C', d and d' and connected to form conductive paths. The conductive path is layered from the bottom to the top of slots) a, a', then from the top to the bottom of slots) b, b',
Next, it proceeds from the bottom of the slot C1C' to the retracted part, and finally from the top to the bottom of the slots d and d'. slot) d, d'
In the illustrated embodiment, the last slot used for the winding of the pole 35 is four. A similar winding structure is used for the opposite pole. Because of the large currents and various electrical and magnetic heating effects that occur, direct cooling of the rotor windings is highly desirable for long-term reliable operation of the generator. For this purpose, matched ventilation holes are provided in the copper wire-wound conductor rods and the rotor is placed in a sealed hydrogen atmosphere. Furthermore, the surface of the rotor core is processed into a scoop shape 34. This process operates to pump hydrogen through the holes in the wound conductor rods as the rotor rotates. In this way, hydrogen gas is immediately introduced into the scoop-shaped opening and forced out through the opening 33 to perform the desired cooling function.

Because of the ventilation holes provided in the winding conductor rods, similar holes are provided in the insulating material within the slots so as not to obstruct this flow of cooling fluid.

FIG. 5 illustrates the invention in one rotor slot. The slots are between rotor teeth extending from rotor core 30. A copper conductor is indicated generally by the reference numeral 42. As can be seen from the figure, a winding insulator 43 is provided between the windings.

The insulator 43 is provided with holes corresponding to those similarly provided in the copper conductor 42 to form cooling fluid passages 46. The four layers connected in parallel are brazed at a certain interval in the longitudinal direction of the slot. Since this brazing is a beneficial brazing, it can be applied to the pail, and the ease of assembling the winding is not impaired. This brazing prevents the formation of copper particles resulting from relative movement of the copper thin layer by inhibiting the relative movement.

Since it is also necessary to insulate the conductive windings 42 from the conductive rotor core, it is necessary to provide a slot insulation sheath 44, typically comprised of glass fiber reinforced epoxy resin. Similarly, an insulating clipage block 41 is used as shown to insulate the windings from the conductive wedge 32. The wedge 32 serves to retain the winding within the slot, particularly during normal high speed operation of the generator. These wedges 32 form dovetail fittings that follow the grooves 40 provided in the rotor teeth 6. <The rust 32 is usually made of @ or aluminum alloy.

The reason why such an alloy is required is that a large centrifugal force is applied to the wedge. In order to increase the strength of the rotor teeth 6, especially near their roots, the slots are preferably tapered to be narrower at the bottom.

FIG. 6 shows one layer of the rotor winding. In the winding section extending longitudinally into the slot, there are two physically and mechanically separate laminae 23, 24. Each lamina is brazed at portion 50 as shown. The use of separate laminae provides cooling with openings 26 through which the cooling fluid is forced under the action of the rotational motion of the rotor when placed in back-to-back adjacent relationship as shown. Grooves can be machined into each thin copper layer 23, 24 so that ducts 25 are formed. However, as mentioned above, in order to prevent copper wear and copper particles from accumulating, the thin layers incorporated into the slots are joined at a certain pitch (by brazing in this example). It can be seen that this is desirable. According to this method, the purpose can be achieved without increasing the slot depth. Also, due to the difference in thermal elongation due to the temperature difference between the thin layers, a shearing force is generated at the brazed part of the field winding corner, but by joining them at a certain interval in the longitudinal direction of the slot, the temperature difference between the thin layers can be reduced. can absorb thermal elongation due to

〔Effect of the invention〕

According to the present invention, by applying brazing between the thin layers of the rotor windings connected in parallel, the depth of the slot becomes deeper and the wear occurs when the anti-wear material is inserted between the thin layers. The generation of copper particles can be prevented without fear of damage to the protective material, thereby preventing ground faults or interlayer short circuit accidents that may occur in conjunction therewith. Therefore, if this method is applied to items that require time and money to repair, such as large generators, it has advantages such as being economically effective and being effective in preventing power outage accidents.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a turbine generator rotor, Fig. 2 is a perspective view showing field windings installed in a pair of rotor slots, and Fig. 3 is a slot end when anti-wear material is provided. FIG. 4 is a perspective view of a rotor illustrating the background of the invention; FIG. 5 is a cross-section of a rotor slot showing the windings inserted into the rotor slot in accordance with the invention; The plan view and FIG. 6 are diagrams showing an example of brazing between the thin layers of a pair of rotor conductor rods. DESCRIPTION OF SYMBOLS 1... Rotor, 3... Field winding, 4... Field winding holding ring, 12... Magnetic pole center, 13... Connection plate, 22
... Wear prevention material, 23.24-Thin layer, 25... Cooling passage, 30... Rotor core, 31... Slot, 3
2... Wedge, 35... Magnetic pole, 40... Passage, 4
1... Clipage block, 42... Winding conductor rod,
43... Insulator, 44... Slot insulation, 46...
・Cooling passage, 47...with brazing, certain 1 hard 0 No. 20 7゜Kaya 5 eyes (long) s Kaya 4 hard

Claims (1)

[Claims] 1. A cylindrical iron core having a longitudinal slot along the outer periphery, and a plurality of series-connected conductive windings arranged in layers within the slot, the layers of the conductive windings being arranged in layers. are kept in series connection by electrical insulators arranged between the layers of the rotating electrically conductive layers, at least one of which is composed of at least two electrically conductive thin layers connected in parallel. A rotor field winding characterized in that the thin layers are joined at a certain interval in the length direction in the rotor field winding.